REGIONAL ANESTHESIA

BACTERIAL CATHETER COLONIZATION: WHAT ARE THE RISK FACTORS?

Abstract

Background:
Although several potential risk factors have been discussed, risk factors associated with bacterial colonization or even
infection of catheters used for regional anesthesia are not very well investigated. Design: The prospective observational
trial. Setting: Department of Anesthesiology Shaheed Beheshti Hospital Shiraz. Period: From April 2003 to April
2004. Materials & Methods:, 297 catheters at several anatomical sites where placed using a standardized technique.
The site of insertion was then monitored daily for signs of infection (secretion at the insertion site, redness, swelling,
or local pain). The catheters were removed when clinically indicated (no or moderate postoperative pain) or when signs
of potential infection occurred. After sterile removal they were prospectively analyzed for colonization, defined as > 15
colony forming units. Results: 50 (16.7%) of all catheters were colonized, and 27 (9.1%) of these with additional signs
of local inflammation. Three of these patients required antibiotic treatment due to superficial infections. Stepwise logistic
regression analysis was used to identify factors associated with catheter colonization. Out of 26 potential factors, three
came out as statistically significant. Catheter placement in the groin (odds-ratio and 95%-confidence interval: 3.4;
1.5–7.8), and repeated changing of the catheter dressing (odds-ratio: 2.1; 1.4–3.3 per removal) increased the risk for
colonization, whereas systemic antibiotics administered postoperatively decreased it (odds ratio: 0.41; 0.12–1.0).
Conclusion Colonization of peripheral and epidural nerve catheter can only in part be predicted at the time of catheter
insertion since two out of three relevant variables that significantly influence the risk can only be recorded
postoperatively. Catheter localization in the groin, removal of the dressing and omission of postoperative antibiotics
were associated with, but were not necessarily causal for bacterial colonization. These factors might help to identify
patients who are at increased risk for catheter colonization.